Chemistry MCQs for NEET — Practice Questions with Answers

The NCERT text states, 'Amines are said to be ‘simple’ when all the alkyl or aryl groups are the same, and ‘mixed’ when they are different.'

Table 9.1 in the NCERT context lists 'Trimethylamine' with the IUPAC name 'N,N-Dimethylmethanamine'.

The NCERT text mentions, 'Two biologically active compounds, namely adrenaline and ephedrine, both containing secondary amino group, are used to increase blood pressure.'

Propan-2-amine ($CH_3CH(NH_2)CH_3$) has only one alkyl group attached to the nitrogen, making it a primary amine. N-Methylethanamine ($CH_3CH_2NHCH_3$) and N,N-Dimethylethanamine ($CH_3CH_2N(CH_3)_2$) are secondary and tertiary amines respectively. Trimethylamine ($(CH_3)_3N$) is a tertiary amine.

The NCERT text states, 'While naming arylamines according to IUPAC system, suffix ‘e’ of arene is replaced by ‘amine’. Thus in IUPAC system, $C_6H_5–NH_2$ is named as benzenamine.'

Table 9.1 in the NCERT context lists 'o-Toluidine' as the common name for '2-Methylaniline'.

The NCERT text mentions, 'Benadryl, a well known antihistaminic drug also contains tertiary amino group.'

According to the NCERT text, 'A combination reaction may be denoted in the manner: A + B \rightarrow C. Either A and B or both A and B must be in the elemental form for such a reaction to be a redox reaction.' In option 3, Carbon (C) and Oxygen ($O_2$) are in their elemental forms, and their oxidation states change (0 to +4 for C, 0 to -2 for O). This makes it a redox combination reaction. Options 1 and 4 are decomposition reactions where elements are formed. Option 2 is a decomposition reaction where no element is formed, and oxidation states do not change, hence it is not a redox reaction.

The NCERT text states, 'In a displacement reaction, an ion (or an atom) in a compound is replaced by an ion'. In this reaction, elemental sodium (Na) displaces hydrogen from water, forming hydrogen gas and sodium hydroxide. Sodium (0 oxidation state) is oxidized to Na(+1), and Hydrogen (+1 in water) is reduced to H(0) in $H_2$. Therefore, it is a displacement redox reaction.

The NCERT text specifies, 'Precisely, a decomposition reaction leads to the breakdown of a compound into two or more components at least one of which must be in the elemental state.' It also clarifies, 'It may also be noted here that all decomposition reactions are not redox reactions. For example, decomposition of calcium carbonate is not a redox reaction.' This directly supports option 2 and refutes option 1. Option 3 is incorrect because if it's a redox reaction, oxidation numbers must change. Option 4 is too restrictive; while some are, not all decomposition reactions are the direct reverse of combination reactions involving only elements.